1. Field of the Invention
This invention relates to an image processing apparatus and, more particularly, to an image processing apparatus for detecting a specific original.
2. Description of the Related Art
Recent improvements in the picture quality of copying machines which now have a color capability have been accompanied by the fear of counterfeiting of specific originals such as bank notes and securities. In order to recognize a specific original in a copying machine or the like, a method such as pattern matching with the shape of an input image has been proposed. For example, in pattern matching, the inclination of an inputted original image is corrected and then the image is matched with an image pattern already registered.
In the example of the prior art described above, however, there is a limit on processing speed and it is difficult to deal with apparatus of higher speeds. In addition, when it is attempted to execute processing simultaneously with regard to a large variety of specific originals, this is difficult to accomplish for the same reason.
Further, in the example of the prior art described above, however, not only is there a limit upon processing speed, but the processing circuitry is complicated as well. As a consequence, it is difficult to deal with processing in a case where there is an increase in the kinds of specific originals to be judged.
One technique for preventing the counterfeiting of bank notes or the like is to register beforehand the data of a specific original in color space and provide means for comparing and collating this data with an input original image, whereby the specific original can be distinguished. Such a technique has been proposed by the present applicant in this application.
With this example of the technique, however, only comparison and collation in the color space are carried out. Consequently, there is the possibility that an image having substantially the same color but a different shape will be judged mistakenly to be the specific original.
Further, the prior-art example described above is such that pattern matching with a specific original is performed after the position and inclination of an original placed upon the platen have been investigated. As a result, high-speed processing is difficult and judgments cannot be made in real-time when the original is scanned.
In the example of the prior art described above, the degree of similarity between an input original and a previously registered specific original is investigated, and the input original is judged to be a specific original when the degree of similarity exceeds a threshold value. This means that an erroneous judgment is highly possible if an original similar to the specific original is inputted.